1. Field of the Invention
This invention relates generally to transducer suspension systems and more particularly to electrical leads for such systems.
2. Description of Prior Art
Direct access storage devices (DASD), or disk drives, store information on concentric tracks of a rotatable magnetic recording disk. A magnetic head or transducer element is moved from track to track to record and read the desired information. Typically, the magnetic head is positioned on an air bearing slider which flies above the surface of the disk as the disk rotates. In some recently proposed disk drives, the slider (or carrier) rides on a liquid film or bearing on the disk. A suspension assembly connects the slider to a rotary or linear actuator. The suspension provides support for the slider.
References which are relevant to transducer suspensions include: U.S. Pat. No. 5,557,489, issued Sep. 17, 1996, by Nakashima et al; U.S. Pat. No. 5,493,074, issued Feb. 20, 1996, by Murata et al; U.S. Pat. No. 5,491,597, issued Feb. 13, 1996, by Bennin et al; U.S. Pat. No. 5,422,764, issued Jan. 6, 1995, by McIlvanie; U.S. Pat. No. 5,384,432, issued Jan. 24, 1995, by Noro, et al; U.S. Pat. No. 4,996,623, issued Feb. 26, 1991, by Erpelding et al; U.S. Pat. No. 4,863,808, issued Feb. 5, 1989 by Sallo; U.S. Pat. No. 4,819,094, issued Feb. 4, 1989, by Oberb; U.S. Pat. No. 4,761,699, issued Aug. 2, 1988, by Ainslie et al; U.S. Pat. 4,703,392, issued Oct. 27, 1987 by Robertson; U.S. Pat. No. 4,543,295, issued Sep. 24, 1985, by Sainte Claire et al; U.S. Pat. No. 1,386,834, issued Aug. 9, 1921 by Beckert; Japanese Application 53-30310, published Mar. 22, 1978, by Takahashi; Japanese Application 6-124558, published May 6, 1994 by Kodaira; Japanese Application 03-347522, published Sep. 28, 1993, by Koomia; Japanese Application 03-193765, published Nov. 18, 1992, by Tadahiro et al; Japanese Application 03-53071, published Oct. 14, 1992, by Wakita et al; Japanese Application 51-104787, published Mar. 22, 1978 by Minoru et al; IBM Technical Disclosure Bulletin, Volume 8, No. 8, January 1966, page 1025, by Webb et al.
The suspension must meet several requirements. The suspension must be flexible and provide a bias force in the vertical direction. This is necessary to provide a compensating force to the lifting force of the air bearings in order to keep the slider at a correct height above the disk. Also, vertical flexibility is needed to allow the slider to be loaded and unloaded away from the disk. Another requirement of the suspension is that it must provide a pivotal connection for the slider. Irregularities in operation may result in misalignment of the slider. The slider is able to compensate for these problems by pitching and/or rolling slightly to maintain the proper orientation necessary for the air bearing. Another requirement of the suspension is that it must be rigid in the lateral direction. This is needed to prevent the head from moving from side to side, which would result in the head reading the wrong track.
Disk drives have become smaller in size and their recording track density has increased dramatically. This has necessitated the use of smaller and smaller heads and suspensions. The smaller size makes it more difficult to string individual wires along the suspension to the head. Recently, it has been proposed that electrical leads be etched directly into the suspension in order to do away with the need to string separate wires. One requirement of these etched leads is that they must be both flexible and highly conductive.
Briefly, in a preferred embodiment of the present invention, a suspension system comprises a rigid load beam member and a layered member. The layered member is comprised of at least four layers: a support layer, an electrically insulating layer, an electrical lead base layer, and an electrically conducting layer. The layered member is etched such that the electrical leads are formed from a combination of the base layer and the conductive layer. The base layer is made of a strong, flexible material which allows the leads to be bent. This is important since leads must be flexible for purposes of manufacture and during operation of the suspension. The electrical conducting layer is made of a highly conductive material which allows for optimum transmission of electrical signals along the leads.
For a fuller understanding of the nature and advantages of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.